Electric mallet



(No Model.)

J. R. PINNEY.

ELEGTEIG MALLET.

Patented Jan. 2, 1883.

ide/2f f N. PETERS4 Pmla-L'vtmgmpim, waulinlun, D4 C,

Wjmesses UNITED STATES PATENT OEEICE.

JOSEPH R. FINNY, OF PITTSBURG, ASSIGNOR TO HIMSELF AND THOMAS Y B. KEER, OF ALLEGHENY CITY, PENNSYLVANIA.

. ELECTRIC MALLET.

SPECIFICATION forming part of Letters Patent N0. 270,187, dated January 2, 1883.

Application filed June 5, 1882. (No model.)

To all whom it may concern:

Be it known that I, JOSEPH R. FINNEY, of Pittsburg, in the county ot' Allegheny and State ot' Pennsylvania, have invented a new and useful Iinprovementin Electric Mallets; and 1 do hereby declare the following to be a full, clear, and exact description thereof', reference being had to the accompanying drawings, forming a part of this specitication, in

IO which- Figure lis a longitudinal section of my improved electric mallet. Fig. 2 is a cross-section on the line :v or, Fig. l; and Fig. 3 is a side view of one of the mallets.

I e Like letters ot' reference indicate like parts in each.

The case (t is for convenience and cheapness composed of three short tubular sections, c', c2, and a3, which are united by screw-threads.

2O In the section a. is an electromagnet, b, having an iron core, b', lianges b2 b3, a knockinghead, b4, and a casing, b5. One of the circuitwires, n, is wrapped in Yany desired number of coils around the core b. The diameter ofthe casing b5 is of a proper size to be in contact with the sides ofthe section c and yet to slide freely therein. The magnet b is shorter than the sect-ion c', in order to permitl it to have any desired length of stroke therein, the length ot' the stroke being regulated by a screw-cap, d,

which closes the outer end of the section c', andv has a shoulder, d', projecting into the interior ot' the bore of the section to act as a stop to gage the axial movement of the mag- 5 net b. The section a2 contains a stationary electro-magnet, c, having an iron core, c', flanges c2 c, and an anvil-head, e". The other circuitwire,p, is wrapped in any desired number ot' coils around the core c. The magnet c 40 is secured iu the section c2 by threading the periphery ofthe ange c3 and screwing it into one end of the section. The section r4.3 has a screw-plug, f, which, when screwed into the end of the section c2, bears against the ange c, and thereby holds the magnet c irmly in place. The mallet g has a stem, g', ofsmaller diameter at its rear end, and a shoulder, g2,

. between the main body and the stem. It tits loosely in the bore "of the section a?, which 5o is of corresponding shape, and the end ofthe stem 'g' projects into a recess formed in the end of the plug j'. Between the contiguous ends of the electro-magnets b and c is a spiral or other suitable spring, h, the coils of which encircle the knocking-head b* andthe anvil o. Extending axially through the cores b c', respectively,are holes bG c6. Through thetlange b"Z is a hole, t'. On the outer end of the magnet c is a U-shaped spring, c, one end of which is fastened to the iiange c3, and the other stands free in the recessj" and extends between thel end ofthe malletstem g and the center'of thc iiange c1.

Thecircuitismadeasfollows: Thewiresused..

are covered with silk or other insulating material, and are both led through the hole d2 in the cap d. One wire, p, passes through bores b(i csof the magnets. lt then extends through a hole, 7c, in the core c', and is wrapped around the core in any desired ,number ot' coils. It then is passed through a hole, l, in the core c', and is fastened in a lead or other suitable washer, c', on the tlange c3, with its end projecting therefrom close to hutnot in contact with the free end of the. spring c. The other wire, a, extends through the hole t around the core b', and thence back, and is Jfastened in the casing b5 at m. The casing b5 is in electrical connection with the metallic case a, which is inelectricalconnection with themalletg. Itthe end g3 of themallet is pressed slightly against an object-say a tooth or illing in the use of a dental mallet-the stem g comes in contact with the spring c and forces it against the project? ingend ot' the nire p and completes the circuit, 85 the cores of the magnets are instantly magnetized, and the movable magnet bis attracted to the stationary magnet` c with sudicient power to overcome the spring lt and to cause the head b4 to deliver a sudden blow upon the anvil c4. The jar upon the whole instrument thus given is concentrated at and delivered by the point g3 ot' the mallet upon the tooth. The slackening of the pressure ot' the hand upon the mallet enables the spring cto leave the point of the wire 17,0pens the circuit, and demagnetizes the cores b c'. The spring 71, then recoils and throws back the movable magnet b. Thus by pressing the mallet lightly in place on the tilling a blow is obtained, and by withdrawing the pressure the circuit is broken and the magnets put in position for another blow.

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.I have shown in Fig. l only two coils of the wires around thecores; but this is merely for elearness ot' illustration. The magnet b has its casing b5 connected with the liange b2, but not with the ange b3. rJhis casing b5, being fromits nature an extension of the core b', brings the poles of the magnet together orinto the same plane, and the arrangement shown enables me to obtain the power ot' two separate electro-magnets with asavingot'bulk, material, and oost. The chiet' value consists` however, in the great power obtained within the restricted limits of the case a'.

I have shown the invention as applied to a dental mallet; butldo notlimit myself to this application, as it is also useful in the construction ot' rock-drills for small forging, driving nails, and for other purposes,in which case the end ot' the malletg is titted for the attachment of properly-shaped bits or tools, or, in other words, is a sliding tool holder.

A screw or other form of gage may be used instead ot the shoulder d ou the cap d, it' desired. It' desired, both ot' the magnets may be provided with the external casing, b5, in which cases the polar ends would be contiguous;I

also, it' desired, the arrangement ot' the wires may be reversed, the positive wire going around the magnet band the negative around the magnet c. An external casing may be made ot' rubber, wood, or other material, it' desired.

I am aware ot' the prior use of electro-magnets as armatures, and do not broadly claim the same; but

What l claim as my invention, and desire to secure by Letters Patent, is-

l. The combination, in an electric mallet or similartool,ot'astationary electro-magnet with a loose electro-magnet having an axial movemeut, the adjacent ends of said magnets having knocking-heads which are contiguous t0 each other, substantially as and for the purposes described.

2. The combination, in an electric mallet or similar tool, of a stationary electro-magnet, a loose electro-magnet having an axial movement, said magnets being provided with coutiguous knocking-heads, and an interposed spring, substantially as and for the purposes described. j

3. The combination, in an electric mallet or similar tool, of a movable electro-magnet, a stationary magnet, the coils ot which are connected to the opposite poles ot' the battery, and which have knocking-heads ou their contigu- 'ous ends, an interposed spring, a mallet capa-4 ble of au axial movement, and a circuit-breaker, substantially as and for the purposes described.

4. The combination, in au electric mallet or similar tool, of a movable electro-magnet for giving the stroke with 'an adjustable stop for determining the length ot' the stroke, substair tially as and for the purposes described.

5. The combination, in an electric mallet or similar tool, of' a spring-contact by which the circuit is made or broken with an axially-moving tool-holder for actuating the spring, substantially as and t'or the purposes described.

G. The combination, in an electric mallet or similar tool, of a loose electro-magnet having an axial movement, and which delivers a blow upon a suitable knocking-head when the circuit is made, with a springI which restores it toits norm-.1l position when thecircuitis broken, substantially as and tor the purpose described.

7. The combination, in an electric mallet or similar tool, ot' a movable electro magnet, which delivers a blow upon a suitable knocking-head when the circuit is made, a circuitbreaker, and a spring for restoring the magnet toits normal position when thecircuitisbroken, substantially asaud for the purposesdescribed.

S. The combination, in an electric mallet or similar tool,ofan electromaguet having its opposite poles brought to the same radial plane, and provided with a knocking-head, in combination with au opposed electro-magnet, also having a knocking-head, substantially as and for the purposes described.

9. The combination, in an electric mallet 01 similar tool, ot' two electro-magnets, one ot' which has an axial movement and both of' which have hollow cores, through which one of the circuit-wires is extended, substantially as and for the purposes described.

l0. The combination, in an electric mallet or similar tool, ot' an electro-magnet formed ot' a core wrapped with one ot' the circuit-wires in electrical contact with the case or other conductor, with a second electro-magnet formed of a core wrapped with the other circuit-wire, and a movable tool in contact with the case, by which thecircuit is completed, substantially as and for the purposes described.

11. The combination, in an electric mallet or similar tool, ot' an elastic metal circuit-breaker with a movable stem or tool electrically connected with one ot' the circuit-wires, by which the elastic circuit-breaker is forced into electrical contact with the other vcircuit wire or conductor, substantially as and lor the purposes described.

ln testimony whereof l have hereunto set my hand this 31st day ot' May, A. D. 1852.

JOSE PH R. FINNEY.

Witnesses:

T. B. KERR, Jantes H. PoR'ru.

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